I understand that the dial of the 15300 was outsourced to Stern Creations while the dial of the 15400 is made in-house, but what exactly has changed?

Would be most grateful if someone could share (macro shots would be awesome).

Bonus question: Petite vs Grande vs Mega Tapasserie - could someone also enlighten me on the key differences? Are they all made in the same ancient manner employed in crafting the dial of the original 5402?